Anthony and Pamela Adams, from Newport, Maggie and Michael Barton, Malcolm Beacham, Terry Brice and Kye Thomas all died in the incident on November 4 2011, which left more than 50 injured.

Geoffrey Counsell, 50, from Somerset, was operating a firework display in a field close to the motorway, at Taunton Rugby Club, at the time and on October 19 last year was charged with seven counts of manslaughter.

But today at Bristol Crown Court the charges were dropped following a review of the case and he now faces being charged under the Health and Safety at Work Act with failing to ensure the safety of others – a charge which carries a maximum sentence of two years in prison.

Leaving court today, Tonia White, 49, whose parents Mr and Mrs Adams were killed on their way back from visiting the family in Taunton, said the torment for the families goes on.

She said: “It’s been a very traumatic experience.

“However we’re confident in the justice system and although the CPS have discontinued the charges of manslaughter, we are led to believe there will be health and safety issues to address and are confident the outcome will remain the same.”

Mrs White was supported by her 24-year-old daughter, Terri, as she fought back tears.

She said she could not describe how she feels about the manslaughter charges being dropped.

“I think we are all still very traumatised and hurt and we’re grieving, and I don’t think that that’s an answer we can give you.”

Asked if the torment is still going on she said: “Yes, very much so, very much so.”

Jean Brice, from Bedminster, Bristol – whose eldest son died in the crash - left court with her husband, 83-year-old Terry Brice.

The 79-year-old said: “It’s a very sensitive case, but what can we say.

“It won’t stop the cruelty and misery that we two 80-year-olds have to go through for the rest of our days.”

Friends and family of the deceased filled the public gallery in the court room to hear the charges dropped.

Peter Blair, prosecuting, said they had reviewed the decision following meetings with a range of experts in different disciplines.

“The outcome of the review that took place and developments, including the additional charge of failing to ensure the safety of others under the Health and Safety Act, was the decision that the prosecution will not be pursuing the manslaughter charges,” he said.

“It is the prosecution’s intention that Mr Counsell will be proceeded against under the Health and Safety Act.”

Adrian Derbyshire, defending, told the court his client should “never have been charged with manslaughter”.

But he added the prosecution had told him it was the right decision at the time and new evidence had come forward that prompted the decision to review the case.

Judge Neil Ford QC said the case would now be marked as a closed file and Counsell left court without comment.

Following the hearing the Crown Prosecution Service said in a statement that it constantly keeps cases under review.

Barry Hughes, chief crown prosecutor for CPS South West, said: “During this review process in December, we sought further advice from a leading expert on the law of negligence and additional information was also provided by expert witnesses and police investigators.

“Based on this additional information and advice, it has been decided that there is insufficient evidence to continue with a prosecution for manslaughter, which will be discontinued by tomorrow.

“Mr Counsell will shortly be charged with an offence under the Health and Safety at Work Act.”

The charge alleges Counsell failed to ensure he operated the firework display so as to ensure, as far as was reasonably practicable, that others who might be affected were not exposed to risks to their health and safety.

Detective superintendent Mike Courtiour, of Avon and Somerset Police, said: “We launched a comprehensive investigation immediately after to establish the full circumstances which led to the collision.

“Our investigation was meticulous and complex. We took hundreds of witness statements, examined 34 vehicles and consulted several experts, including meteorologists, pyrotechnic and forensic specialists.

“Based on this evidence the Crown Prosecution Service took a decision to charge. However, following further consideration in recent weeks they have decided to drop the manslaughter charges.”

Those that lost their lives were Lorry drivers Mr Brice, from Patchway, south Gloucestershire, and Mr Thomas, from Gunnislake, Cornwall, with father and daughter Mr and Miss Barton, from Windsor, Berkshire, grandparents Mr and Mrs Adams, from Newport, and battle re-enactor Mr Beacham, from Woolavington, near Bridgwater.